W5 Two-way Coupled Irrigation Design Document
The Design Document page provides a description of the algorithms, implementation and planned testing including unit, verification, validation and performance testing. Please read Step 1.3 Performance Expectations that explains feature documentation requirements from the performance group point of view.
Design Document
In the table below 4.Equ means Equations and Algorithms, 5.Ver means Verification, 6.Perf - Performance, 7. Val - Validation, 
- competed, 
- in progress, 
- not done
Overview table for the owner and an approver of this feature
1.Description | This is a descriptive long title |
| 2.Owner | |
| 3.Created | |
| 4.Equ | |
| 5.Ver | |
| 6.Perf | |
| 7.Val | |
| 8.Approver | |
| 9.Approved Date | |
| V2.0 |
Title: Two-way coupled irrigation scheme
Requirements and Design
E3SM Watercycle Group
Date:
Summary
Requirements
Requirement: Coupling irrigation water withdrawal between ELM and MOSART
Date last modified:
Contributors: Anthony Craig, Guoyong Leng (Unlicensed), Tian Zhou
Each requirement is to be listed under a ”section” heading, as there will be a one-to-one correspondence between requirements, design, proposed imple- mentation and testing. Requirements should not discuss technical software issues, but rather focus on model capability. To the extent possible, require- ments should be relatively independent of each other, thus allowing a clean design solution, implementation and testing plan.
Algorithmic Formulations
Design solution: At each coupling time step, following steps will be performed: 1) ELM evaluates the soil moisture deficits and determines the irrigation demand at grid level. 2) The irrigation demand will be split into surface water and groundwater irrigation demand based on a predefined fraction. 3) The surface water demand will be sent to MOSART through coupler. 4) MOSART determines the irrigation supply based on the local runoff, streamflow, and upstream reservoir storage. 5) Irrigation supply will be sent back to ELM through the coupler. 6) ELM applies irrigation which is the sum of the surface water irrigation supply from MOSART and groundwater irrigation which is assumed always met.
Date last modified:
Contributors: Anthony Craig, Guoyong Leng (Unlicensed), Tian Zhou.
Design and Implementation
Implementation: Pull request about this implementation (https://github.com/E3SM-Project/E3SM/pull/3074)
Date last modified:
Contributors: Anthony Craig, Tian Zhou
surfrdMod.F90
Around **line 650** there are about 10 lines related to the surface water only or both surface and groundwater, as well as the `ldomain%firrig` values. If all commented out, it would be surface water only, with `ldomain%firrig` = 0.7.
CanopyHydrologyMod.F90
Around **line 456** there are a few lines about how to calculate the actual irrigation `qflx_real_irrig(p)`. When it's onw-way coupling, it equals to the demand `qflx_irrig(p)`. If two-way coupling, it's the sum of the surface water and groundwater irrigation. In either case, this vaule cannot be greater than the demand `qflx_irrig(p)`.
CanopyFluxesMod.F90
Around **line 447**, the `irrig_nsteps_per_day` is defined. This value does not have unit. It depends on the size of the time step `dtime` in second and the length of the irrigation period `irrig_length`. Currently the `irrig_length` is hard coded at **line 155** as 14400 secounds (4 hrs), starting at 6 o'clock everyday (defined by `irrig_start_time`).
Another important variable used here is the `deficit`, which is daily irrigation water need to be applied to the soil (mm). It depends on the calibratable term `ldomain%firrig(g)`.
SoilHydrologyMod.F90
This is the code that takes care of the groundwater level in the soil. I updated the **lines 717-718** by replacing the `qflx_irrig(c)*ldomain%f_grd(g) ` with `qflx_grnd_irrig_col(c)` calculated in `CanopyHydrologyMod.F90` as these two are not the same anymore.
WaterfluxType.F90
A number of new variables I created are defined here. Also around **lines 352 and 435**, the output variables in the netCDF file are also defined.
HydrologyDrainageMod.F90
I updated the `qflx_irr_demand(c)` in **line 281**. This variable is the surface water irrigation demand ready to be sent to MOSART.
clm_varctl.F90
I created a flag `tw_irr` to control one way or two way coupling. True is two way, false is one way. Need to put it in the namelist file in the future.
BalanceCheckMod.F90
Around **line 323** I updated the equation for water balance error calculations:
Planned Verification and Unit Testing
Verification and Unit Testing: B4B tests passed
Date last modified:
Contributors: Tian Zhou
E3SM land modeler b4b tests were performed and passed with the two-way coupling turned off.
Planned Validation Testing
Validation Testing: 30 year simulations with and without two-way irrigation
Date last modified:
Contributors: Tian Zhou
A set of 30-year simulation experiments were performed with different model configurations including 1-way coupled surface water irrigation only; 1-way coupled surface water and groundwater irrigation; 2-way coupled surface water irrigation only; 2-way coupled surface water and groundwater irrigation. These simulation experiments produced reasonable results. See details in Zhou et al. (submitted)
Zhou, T; L. R. Leung; G. Leng; N. Voisin; H. Li; A. P. Craig; T. Tesfa; Y. Mao (in review). Global irrigation characteristics and effects simulated by fully coupled land surface, river, and water management models in E3SM. Journal of Advances in Modeling Earth Systems
Planned Performance Testing
Performance Testing: short-desciption-of-testing-here
Date last modified:
Contributors: (add your name to this list if it does not appear)
How will XXX be tested? i.e. how will be we know when we have met requirement XXX. Will these unit tests be included in the ongoing going forward?